Biden, a former vice president, defeated Trump in a keenly-contested election last November with 306 electoral votes.

For weeks since then, Trump repeated disproved claims of electoral malpractice and voter fraud, insisting instead that he won by a wide margin.

The Republican president also launched numerous lawsuits that failed in courts, and made a last-ditch attempt to force Congress to reject the result during a vote certification exercise on Wednesday, January 6, 2021.

However, after hours of delay, Biden's victory was affirmed by a joint session of the U.S. Congress presided by Trump's vice president, Mike Pence.

"Even though I totally disagree with the outcome of the election, and the facts bear me out, nevertheless there will be an orderly transition on January 20th," Trump said in a statement.

"I have always said we would continue our fight to ensure that only legal votes were counted. While this represents the end of the greatest first term in presidential history, it's only the beginning of our fight to Make America Great Again," he added.

Biden's final and official victory came hours after Trump supporters invaded the U.S. Capitol Building in Washington DC while lawmakers were certifying the result of the November election.

Lawmakers were evacuated as rioters shockingly laid siege to the building and vandalised property, leading to the imposition of a curfew in the U.S. capital.

One person was shot dead by security officials during the invasion, while three others reportedly died from medical emergencies.

The rioters' action was blamed on Trump who was subsequently suspended on Twitter and Facebook for inciting violence.

Attempts by pro-Trump lawmakers to block certification of the result expectedly failed after the joint session reconvened.